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authorThomas Gleixner <tglx@linutronix.de>2009-12-10 15:35:10 +0100
committerThomas Gleixner <tglx@linutronix.de>2009-12-11 10:28:08 +0100
commitbb6eddf7676e1c1f3e637aa93c5224488d99036f (patch)
tree3256cb7ea6954f28b0bb3ccee2db570e3d0ff762
parente9c0748b687aa70179a9e6d8ffc24b2874fe350b (diff)
clockevents: Prevent clockevent_devices list corruption on cpu hotplug
Xiaotian Feng triggered a list corruption in the clock events list on CPU hotplug and debugged the root cause. If a CPU registers more than one per cpu clock event device, then only the active clock event device is removed on CPU_DEAD. The unused devices are kept in the clock events device list. On CPU up the clock event devices are registered again, which means that we list_add an already enqueued list_head. That results in list corruption. Resolve this by removing all devices which are associated to the dead CPU on CPU_DEAD. Reported-by: Xiaotian Feng <dfeng@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Xiaotian Feng <dfeng@redhat.com> Cc: stable@kernel.org
-rw-r--r--kernel/time/clockevents.c18
1 files changed, 15 insertions, 3 deletions
diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index 20a8920029e..91db2e33d86 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -238,8 +238,9 @@ void clockevents_exchange_device(struct clock_event_device *old,
*/
void clockevents_notify(unsigned long reason, void *arg)
{
- struct list_head *node, *tmp;
+ struct clock_event_device *dev, *tmp;
unsigned long flags;
+ int cpu;
spin_lock_irqsave(&clockevents_lock, flags);
clockevents_do_notify(reason, arg);
@@ -250,8 +251,19 @@ void clockevents_notify(unsigned long reason, void *arg)
* Unregister the clock event devices which were
* released from the users in the notify chain.
*/
- list_for_each_safe(node, tmp, &clockevents_released)
- list_del(node);
+ list_for_each_entry_safe(dev, tmp, &clockevents_released, list)
+ list_del(&dev->list);
+ /*
+ * Now check whether the CPU has left unused per cpu devices
+ */
+ cpu = *((int *)arg);
+ list_for_each_entry_safe(dev, tmp, &clockevent_devices, list) {
+ if (cpumask_test_cpu(cpu, dev->cpumask) &&
+ cpumask_weight(dev->cpumask) == 1) {
+ BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);
+ list_del(&dev->list);
+ }
+ }
break;
default:
break;